Frasier says he and Lilith have been married 7 years. At this point in time, they would be approaching their 5th wedding anniversary (1988-1993). They have been seeing each other since 1986, which was 7 years ago from 1993, but have not been married that whole time.
(Whilst Shauna and her boyfriend make out, Frasier plays Yahtzee with her parents.)
Frasier: (rolls dice) Yahtzee!!!
Cliff: I guess we better tell them before Bigfoot comes in and starts singing the anniversary waltz.
Peter: If you're in the video business, why are you dressed as a mailman?
Cliff: ...Costume party down at the Directors' Guild.
(Sam says that Frasier should date Shauna)
Frasier: Look, I just came off a seven year marriage. It's hard to think of replacing Lilith.
Carla: Just go to the morgue and open any drawer.
Cliff: We are going to jail, Norm.
[The guests have arrived at Cheers for their family reunion]
Rebecca: I took the liberty of making name-tags for everybody. See: "Hello, My name's Rebecca". And this one is for you, Peter. [to Party Guest #1] And your name is...
Party Guest #1: We're all family. We know each other's names. [she walks away]
Rebecca: Let me make one out for you anyway: "B-I-T-C..."